"The U.S. Constitution establishes a system of dual sovereignty between the states and the federal government, with each state having its own government, endowed with all the functions essential to separate and independent existence. Although the Supremacy Clause of the Constitution designates 'the Laws of the United States' as 'the supreme Law of the Land,' other provisions of the Constitution--as well as legal principles undergirding those provisions--nonetheless prohibit the national government from enacting certain types of laws that impinge upon state sovereignty.The various principles that delineate the proper boundaries between the powers of the federal and state governments are collectively known as 'federalism.' Federalism-based restrictions that the Constitution imposes on the national government's ability to enact legislation may inform Congress's work in any number of areas of law in which the states and the federal government dually operate."